Clinically Proven Reduces Colic and Discomfort Designed to Reduce Gas Airflex Venting System Reduces Air Ingestion Ribbed Texture Prevents Nipple Collapse for Uninterrupted Feeding Fewer Parts for Easy Cleaning and Assembly BPA Free #1 Reusable Bottle Brand Our clinically-proven Airflex venting system is designed to reduce colic and gas. The nipple shape and the ribbed texture help prevent collapse for uninterrupted, comfortable feeding. As your baby feeds, the unique integrated valve flexes to allow air into the bottle, away from baby's tummy to help reduce gas, spit-up and burping. With its wide neck and fewer parts, our bottle is easier to assemble and to clean quickly and thoroughly. Clinically Proven: Clinical studies have shown that the Phillips Avent bottle reduces colic and fussing. Fussing is significantly reduced at night as babies fed with Phillips Avent anti-colic bottles experienced 60% less fussing that babies fed with a leading competitor's vented bottle.